PCI express to PCI express based low latency interconnect scheme for clustering systems

ABSTRACT

PCI Express is a Bus or I/O interconnect standard for use inside the computer or embedded system enabling faster data transfers to and from peripheral devices. The standard is still evolving but has achieved a degree of stability such that other applications can be implemented using PCIE as basis. A PCIE based interconnect scheme to enable switching and inter-connection between external systems, such that the scalability can be applied to enable data transport between connected systems to form a cluster of systems is proposed. These connected systems can be any computing or embedded system. The scalability of the interconnect will allow the cluster to grow the bandwidth between the systems as they become necessary without changing to a different connection architecture.

FIELD OF INVENTION

This invention relates to cluster interconnect architecture for high-speed and low latency information and data transfer between the systems in the configuration.

BACKGROUND AND PRIOR ART

The need for high speed and low latency cluster interconnect scheme for data and information transport between systems have been recognized as one needing attention in recent times. The growth of interconnected and distributed processing schemes have made it essential that high speed interconnect schemes be defined and established to provide the speed up the processing and data sharing between these systems.

There are interconnect schemes that allow data transfer at high speeds, the most common and fast one existing today is the Ethernet connection allowing transport speeds from 10 MB to as high as 10 GB/sec. TCP/IP protocols used with Ethernet have high over head with inherent latency that make it unsuitable for some distributed applications. Effort is under way in different areas of data transport to reduce the latency of the interconnect as this is a limitation on growth of the distributed computing power.

What is Proposed

PCI Express (PCIE) is an emerging I/O interconnect standard for use inside computers, or embedded systems that allow serial high speed data transfer to and from peripheral devices. The typical PCIE provides 2.5 GB transfer rate per link (this may change as the standard and data rates change). Since the PCIE standard is starting become firm and used within the systems, what is disclosed is the use of PCIE standard based peripheral as an interconnect between systems, typically through an interconnect module or a switch. This interconnect scheme can reduces the latencies of communication in a cluster. The PCIE standard based peripheral provide for increase in the number of links per connection as band width needs increase and thereby allow scaling of the band width available within any single interconnect or the system of interconnects. This will allow the interconnect architecture to remain constant as the interconnect band width need goes from 2.5 GB with a X1 link (single data link) to much higher values of 10 GB with a X4 link (4 data links), 40 GB with a X16 link (16 data links) or a 80 GB with a X32 link (32 data links) and so on providing for easy scaling of the multi-system cluster.

Some Advantages of the Proposed Connection Scheme:

1. Reduced Latency of Data transfer as conversion from PCIE to other protocols like eathernet is avoided during transfer.

2. The number of links per connection can scale from X1 to larger numbers X32 or even X64 possible based on the bandwidth needed.

3. Minimum change in interconnect architecture is needed with increased bandwidth, enabling easy scaling with need.

4. Standardization of the PCIE based peripheral will make components easily available from multiple vendors, making the implementation of interconnect scheme easier and cheaper.

5. The PCIE based peripheral to PCIE based peripheral links in connections allow ease of software control and provide reliable bandwidth.

DESCRIPTION OF FIGURES

FIG. 1 Typical Interconnected (multi-system) cluster (shown with eight systems)

FIG. 2 A cluster using multiple interconnect modules or switches to interconnect smaller clusters.

EXPLANATION OF NUMBERING AND LETTERING IN THE FIG. 1

(1) to (8): Number of Systems interconnected in FIG. 1

(9): Switch sub-system.

(10): Software configuration and control input for the switch.

(1 a) to (8 a): PCI Express based peripheral module (PCIE Modules) attached to systems.

(1 b) to (8 b): PCI Express based peripheral modules (PCIE Modules) at switch.

(1L) to (8L): PCIE based peripheral module to PCIE based peripheral module connections having n-links (n-data links)

Explanation of Numbering and Lettering in the FIG. 2

(12-1) and (12-2): clusters

(9-1) and (9-2):interconnect modules or switch sub-systems.

(10-1) and (10-2): Software configuration inputs

(11-1) and (11-2): Switch to switch interconnect module in the cluster

(11L): Switch to switch interconnection

DESCRIPTION OF THE INVENTION

FIG. 1 is a typical cluster interconnect. The Multi-system cluster shown consist of eight units or systems {(1) to (8)} that are to be interconnected. Each system has a PCI express (PCIE) based peripheral module {(1 a) to (8 a)} as an IO module, at the interconnect port, with n-links built into or attached to the system. (9) is an interconnect module or a switch sub-system, which has number of PCIE based interconnect modules equal to or more than the number of systems to be interconnected, in this case of FIG. 1 this number being eight {(1 b) to (8 b)}, that can be interconnected for data transfer through the switch. A software based control input is provided to configure and/or control the operation of the switch. Link connections {(1L) to (8L)} attach the PCIE based peripheral modules on the respective systems to those on the switch with n links. The value of n can vary depending on the connect band width required by the system.

When data has to be transferred between say system 1 and system 5, in the simple case, the control is used to establish an internal link between PCIE based peripheral modules 1 b and 5 b inside the switch. The hand shake is established between out bound PCIE 1 a and inbound PCIE module 1 b and out bound PCI module 5 a and inbound module 5 b. This provides a through connection between the PCI modules 1 a to 5 a through the switch allowing data transfer. Data can then be transferred at speed between the modules and hence between systems. In more complex cases data can also be transferred and qued in storage implemented in the switch and then when links are free transferred out to the right systems at speed.

Multiple systems can be interconnected at one time to form a multi-system that allow data and information transfer and sharing through the switch. It is also possible to connect smaller clusters together to take advantage of the growth in system volume by using an available connection scheme that interconnects the switches that form a node of the cluster.

If need for higher bandwidth and low latency data transfers between systems increase, the connections can grow by increasing the number of links connecting the PCIE modules between the systems in the cluster and the switch without completely changing the architecture of the interconnect. This scalability is of great importance in retaining flexibility for growth and scaling of the cluster.

It should be understood that the system may consist of peripheral devices, storage devices and processors and any other communication devices. The interconnect is agnostic to the type of device as long as they have a PCIE module at the port to enable the connection to the switch. This feature will reduce the cost of expanding the system by changing the switch interconnect density alone for growth of the multi-system.

PCIE is currently being standardized and that will enable the use of the existing PCIE modules to be used from different vendors to reduce the over all cost of the system. In addition using a standardized module in the system as well as the switch will allow the cost of software development to be reduced and in the long run use available software to configure and run the systems.

As the expansion of the cluster in terms of number of systems, connected, bandwidth usage and control will all be cost effective, it is expected the over all system cost can be reduced and over all performance improved by standardized PCIE module use with standardized software control.

Typical connect operation may be explained with reference to two of the systems, example system(1) and system (5). System (1) has a PCIE module (1 a) at the interconnect port and that is connected by the connection link or data-link or link (1L) to a PCIE module (1 b) at the IO port of the switch(9). System(5) is similarly connected to the switch trough the PCIE module (5 a) at its interconnect port to the PCIE module(5 b) at the switch(9) IO port by link (5L). Each PCIE module operates for transfer of data to and from it by standard PCI Express protocols, provided by the configuration software loaded into the PCIE modules and switch. The switch operates by the software control and configuration loaded in through the software configuration input.

FIG. 2 is that of a multi-switch cluster. As the need tom interconnect larger number of systems increase, it will be optimum to interconnect multiple switches of the clusters to form a new larger cluster. Such a connection is shown in FIG. 2. The shown connection is for two smaller clusters (12-1 and 12-2) interconnected using PCIE modules that can be connected together using any low latency switch to switch connection (11-10 and 11-2), connected using interconnect links (11L) to provide sufficient band width for the connection. The switch to switch connection transmits and receives data and information using any suitable protocol and the switches provide the interconnection internally through the software configuration loaded into them.

The following are some of the advantages of the disclosed interconnect scheme

1. Provide a low latency interconnect for the cluster.

2. Use of PCIExpress based protocols for data and information transfer within the cluster.

3. Ease of growth in bandwidth as the system requirements increase by increasing the number of links within the cluster.

4. Standardized PCIE component use in the cluster reduce initial cost.

5. Lower cost of growth due to standardization of hardware and software.

6. Path of expansion from a small cluster to larger clusters as need grows.

7. Future proofed system architecture.

In fact the disclosed interconnect scheme provides advantages for low latency multi-system cluster growth that are not available from any other source. 

1. An interconnected cluster comprising multiple systems and at least a switch, where each system has a PCIExpress based peripheral module (PCIE Module) at the interconnect port and the switch has sufficient number of IO ports available each with PCIExpress based peripheral modules to connect the number of systems in the cluster to the switch.
 2. The interconnected cluster comprising of multiple systems and the switch in claim 1, where in, each system is connected to the switch by one or more data links connected between the PCIE module at the system interconnect port and one of the PCIE module at the IO port of the switch.
 3. The interconnected cluster comprising of multiple systems and the switch in claim 1, where in, the connection between the PCIE module at the interconnect port of the system and the connected PCIE modules at the IO port of the switch can be by using multiple data links as the bandwidth requirements of the interconnect demand.
 4. The interconnected cluster comprising of multiple systems and the switch in claim 1, where in, the switching between the IO ports inside the switch is controlled by the configuration software loaded into the switch.
 5. The interconnected cluster comprising of multiple systems and the switch in claim 1, where in, the data and information transfer between each PCIE module at the system and the interconnected PCIE module at the IO port of the switch is by using protocol based on PCI Express.
 6. An interconnected cluster system comprising of two or more smaller clusters to form a larger cluster, each small cluster having multiple systems and a switch, having suitable low latency interconnection between switches of the small clusters to allow the over all system growth.
 7. The interconnected cluster system comprising of two or more smaller clusters having multiple systems and a switch each, of claim 6, where in, the interconnection between switches is scalable.
 8. The interconnected cluster system comprising of two or more clusters having multiple systems and a switch each, of claim 6, where in, the cluster growth can take place without changing the architecture of the individual small clusters. 